When molding a green tire with a tire molding apparatus, first, ring-shaped bead wires are fitted to bead portions, the both edges, of a cylindrically formed carcass ply. Then, the bead portions of the carcass ply are supported by a pair of movable bodies, which can approach and move away from each other along a main shaft of a molding drum (widthwise of the tire to be molded). A bladder made of elastic material, such as rubber, is fitted between the movable bodies, and the carcass ply is disposed thereon. Next, the bladder is supplied with compressed air to be closely contacted with the inner periphery of the carcass ply, thereby swelling and diametrically expanding the middle portion of the carcass ply, axially of the main shaft of the drum, through the bladder. At the same time, the bead portions of the carcass ply are brought close to each other by the movable bodies. Then, by swinging folding mechanisms mounted on the movable bodies from a closed position, where their ends are pointing axially inward, to an open position, where their ends are pointing the other way from the main shaft (radially outward of the tire), the carcass ply is folded to the periphery of the bead portions with folding members provided on the ends of the folding mechanisms. Finally, a belt-tread band, formed into a ring shape by pressing them together beforehand is fitted on the outer surface of the carcass ply, and the green tire is completed.
FIG. 9 is a front sectional view of a conventional tire molding apparatus (refer to Patent document 1), and FIG. 10 is a front sectional view of the vicinity of a bead lock segment of the tire molding apparatus of FIG. 9.
In FIG. 9 and FIG. 10, a tire molding drum 21 used in molding a green tire has a horizontal, cylindrical main shaft of the drum 22. This main shaft of the drum 22 is connected to a driver (not shown) of the tire molding apparatus and can be rotated about its axis by the driver. FIG. 11 is a schematic view of the folding mechanism on the left side of the tire molding apparatus in FIG. 9, wherein FIG. 11A shows a state before folding, and FIG. 11B shows a state during folding.
The main shaft of the drum 22 is inserted with a screw axis 23, coaxial with the main shaft of the drum 22, in a rotatable manner. The screw axis 23 has external threads 24 and 25, threaded reversely to each other, on axially both sides of the circumference thereof. A plurality of axially extending slits 26 and 27 are provided in the main shaft of the drum 22, on the portion overlapping the external threads 24 and 25, respectively. These slits 26 and 27 are provided in a plural number around the circumference and equally spaced from each other. Nuts 28 and 29 threadably fit the external threads 24 and 25, respectively, and are fixed with connecting blocks 30 and 31, which pass through the slits 26 and 27, respectively.
On axially both sides of the main shaft of the drum 22, there are provided generally cylindrical sliding bodies 35 and 36, supported in an axially movable manner and surrounding the main shaft of the drum 22. The connecting blocks 30 and 31 are connected to the sliding bodies 35 and 36, respectively, at the axially inner ends of the sliding bodies 35 and 36. The connecting blocks 30 and 31, and the sliding bodies 35 and 36 collectively configure a pair of movable bodies 37 and 38, supported on axially both sides of the main shaft of the drum 22 in an axially movable manner.
When the screw axis 23 is driven and rotated by the driver of the tire molding apparatus, these movable bodies 37 and 38 move in opposite directions by an equal distance to approach or move away from each other due to the external threads 24 and 25, threaded reversely to each other. The screw axis 23 and the nuts 28 and 29 collectively configure an approaching/separating means 40, which moves the movable bodies 37 and 38 in opposite directions by an equal distance to make them approach or move away from each other.
At the axially inner ends of the sliding bodies 35 and 36, there are provided a plurality of housing holes 42 and 43, which extend radially of the sliding bodies 35 and 36, respectively. These housing holes 42 and 43 are provided in a plural number along the circumference of the sliding bodies 35 and 36 and equally spaced from each other. The housing holes 42 and 43 of the sliding bodies 35 and 36 (the movable bodies 37 and 38) are inserted with and supporting bead lock segments 44 and 45 in a radially movable manner, respectively. On the radially outer ends of the bead lock segments 44 and 45, there are formed axially outwardly projecting finger receivers 46 and 47 respectively, on which ends of folding fingers, more specifically, folding rollers, described later, will be placed. And when the rollers are placed on the bead lock segments, the radially outer ends of the folding rollers and the same of the bead lock segments 44 and 45 will be generally aligned.
In the sliding bodies 35 and 36, there are formed ring-shaped cylinder chambers 48 and 49, each of which housing a ring-shaped piston 50 and 51 in an axially movable manner, which divide the cylinder chambers 48 and 49 into inner chambers 48a and 49a and outer chambers 48b and 49b, respectively. These pistons 50 and 51 have integrally-formed extending parts 50a and 51a, which extend axially inward through axially inner walls of the cylinder chambers 48 and 49. Linkages 53 and 54, provided in a plural number, are connected to the bead lock segments 44 and 45 at one end, and to the axially inner ends of the extending parts 50a and 51a at the other end, respectively, in a pivotable manner. The linkages 53 and 54 are disposed at a slant so as to open into axially inward.
When a high-pressure fluid is supplied into the inner chambers 48a and 49a of the cylinder chambers 48 and 49 from a fluid source (not shown), pistons 50 and 51 move axially outward, which moves the bead lock segments 44 and 45 radially inward. On the other hand, when the high-pressure fluid is supplied into the outer chambers 48b and 49b, pistons 50 and 51 move axially inward, which moves the bead lock segments 44 and 45 radially outward. The pistons 50 and 51, and the linkages 53 and 54 collectively configure an expansion/contraction means 55, which expands and contracts the bead lock segments 44 and 45 by radially and synchronously moving them.
There are provided a pair of sealing members 58 and 59 made of rubber-coated cord cloth, which seal between the movable bodies 37 and 38, including the bead lock segments 44 and 45, and a tire component K, described later, when the tire component K is supported from the radially inward by the bead lock segments 44 and 45 having been diametrically expanded by the expansion/contraction means 55.
The sealing members 58 and 59 have base ends 58a and 59a, airtightly fixed to the top ends of the movable bodies 37 and 38 (the sliding bodies 35 and 36) which are axially more inward than the bead lock segments 44 and 45. And from the radially outer ends of the base ends 58a and 59a, there are axially inwardly extending cylindrical, inward-extending parts 58b and 59b. From the axially inner ends of the inward-extending parts 58b and 59b, there are axially outwardly extending outward-extending parts 58c and 59c, also cylindrical and broader than the inward-extending parts 58b and 59b, overlying the inward-extending parts 58b and 59b radially outwardly.
On the axially middle of the outer surface of the movable bodies 37 and 38, more specifically, the sliding bodies 35 and 36, there are formed flanges 61 and 62, to the outside of which cylindrical bodies 63 and 64 are fitted in an axially movable manner. The cylindrical bodies 63 and 64 have integrally-formed flanges 65 and 66 on the inner surface of the axially outer ends. Base ends (axially outer ends) of folding fingers 101 and 111, provided in a plural number around the circumference at equal angles, are connected to the flanges 65 and 67 in a manner capable of swinging on axes of swing 107 and 117 (the center of swing).
The folding fingers 101 and 111 are configured to be generally L-shape in the front view, with horizontal fingers 102 and 112, which point axially inward of the main shaft of the drum 22 (rightward in the drawing) in the closed position, and supporting fingers 103 and 113, which extend substantially perpendicular to the axial direction from base ends of the horizontal fingers 102 and 112. On the ends of the horizontal fingers 102 and 112, there are fitted folding rollers 104 and 114 in a rotatable manner. Further, the horizontal fingers 102 and 112 are fitted with restoration members 105, 106, 115, and 116 made of elastic material such as rubber band on the middle of the fingers, in a manner surrounding them from the outside. As the folding mechanisms are disposed in a plural number along the circumference of the main shaft of the drum 22 at equal angles, the restoration members 105, 106, 115, and 116 restrain the horizontal fingers of these folding mechanisms in a manner bundling them. On radially outward of the folding fingers 101 and 111, there is disposed the tire component K, on which filler-fitted beads B, including bead cores and bead fillers are disposed.
The cylindrical bodies 63 and 64 have integrally-formed ring-shaped flanges 71 and 72 on the inner surface of the axially inner ends. These flanges 71 and 72 slidably contact parts of the sliding bodies 35 and 36, which are axially more inward than the flanges 61 and 62. And when the high-pressure fluid is supplied into inner cylinder chambers 73 and 74, formed between the flanges 61, 62, and the flanges 71, 72 from a fluid source (not shown), the cylindrical bodies 63 and 64 move axially inward. At this time, the folding fingers 101 and 111 move axially inward with the cylindrical bodies 63 and 64 and open, by which the tire components K axially extending out of the filler-fitted beads B is folded to the periphery of the filler-fitted beads B.
There are fitted cylindrical stopper bodies 77 and 78 on parts of the outer surface of the sliding bodies 35 and 36, which are axially more outward than the flanges 61 and 62. The stopper bodies 77 and 78 slidably engage the flanges 65, and 66 on their circumferences. When the high-pressure fluid is supplied into the outer cylinder chambers 79 and 80, formed between the flanges 61, 62 and the flanges 65, 66 from the fluid source, the folding fingers 101 and 111 move axially outward with the cylindrical bodies 63 and 64, and close.
The stopper bodies 77 and 78 have integrally-formed, radially outwardly projecting flange-shaped stoppers 85 and 86 on the axially inner ends thereof. These stoppers 85 and 86 set a limit that stop the inward movement of the cylindrical bodies 63 and 64 when the flanges 65 and 66 move axially inward of the main shaft and come into contact with the stoppers.
Now, action of the tire molding apparatus having the above configuration will be described. When molding a green tire using the tire molding drum 21, first, the tire component K, including an innerliner and a carcass ply, filler-fitted beads B, and a belt-tread band T which have been molded into a cylindrical shape with the other molding drums, are conveyed to the outside of the tire molding drum 21 by a conveying apparatus and fitted together.
Next, by supplying a high-pressure fluid into the outer chambers 48b and 49b of the cylinder chambers 48 and 49, the pistons 50 and 51 are moved axially inward. Because the bead lock segments 44 and 45 are connected to the pistons 50 and 51 through the linkages 53 and 54, the bead lock segments 44 and 45, being guided by the housing holes 42 and 43, move radially outward of the tire and expand diametrically. And the bead lock segments 44 and 45 support the tire component K and the filler-fitted beads B from radially inward of the tire through the outward-extending parts 58c and 59c of the sealing members 58 and 59.
At this time, because the folding rollers 104 and 114 of the folding fingers 101 and 111 are placed on the finger receivers 46 and 47 of the bead lock segments 44 and 45, the folding rollers 104 and 114 move radially outward with the bead lock segments 44 and 45 by the same distance, which slightly swings the folding fingers 101 and 111 toward the open position. As a result, the tire component K axially extending out of the filler-fitted beads B is always supported by the folding rollers 104 and 114 from the radially inward, and will not droop on the axially outer surface of the bead lock segments 44 and 45 and produce unevenness.
Next, with supplying air into a space S surrounded by the sliding bodies 35 and 36 and the tire component K extending between the filler-fitted beads B, the screw axis 23 is rotated. This causes the external threads 24 and 25 to be rotated, and the movable bodies 37 and 38, the bead lock segments 44 and 45, and the folding fingers 101 and 111 are integrally moved axially inward and brought together. By this, the tire component K extending between the filler-fitted beads B is gradually transformed into a toroidal shape. When the movable bodies 37 and 38 move axially inward to a predetermined position, the rotation of the screw axis 23 is stopped, though the air is continued to be supplied into the space S. As a result, the tire component K transforming into a toroidal shape contacts the belt-tread band T, with the axially middle part thereof closely contacting the inner periphery of the belt-tread band T. At this time, the internal pressure of the space S is maintained by the sealing members 58 and 59.
Then, by supplying the high-pressure fluid into the inner cylinder chambers 73 and 74, the cylindrical bodies 63 and 64, and the folding fingers 101 and 111 are moved axially inward. At this time, because the folding rollers 104 and 114 come into contact with the filler-fitted beads B, extending generally radially, the rollers move generally radially outward along the axially outer surface of the filler-fitted beads B. And as shown in FIG. 11B, the rollers fold the tire component K axially extending out of the filler-fitted beads B radially outward, on the filler-fitted beads B. This radially outward movement of the folding rollers 104 and 114 causes the folding fingers 101 and 111 to simultaneously swing toward the open position.
When the folding rollers 104 and 114 of the folding fingers 101 and 111 swinging toward the open position completely fold the tire component K axially extending out of the filler-fitted beads B, the flanges 65 and 66 of the cylindrical bodies 63 and 64 come into contact with the stoppers 85 and 86 of the stopper bodies 77 and 78. By this, axially inward movement of the cylindrical bodies 63 and 64 is stopped. This state is shown in the lower half of the FIG. 9.
Next, by supplying the high-pressure fluid into the outer cylinder chambers 79 and 80, the cylindrical bodies 63 and 64 and the folding fingers 101 and 111 are moved axially outward until the flanges 71 and 72 come into contact with the flanges 61 and 62. At this time, receiving elastic restoring force of the restoration members 105, 106, 115, and 116, the folding fingers 101 and 111 swing toward the closed position until the folding rollers 104 and 114 are placed on the finger receivers 46 and 47.
Then, with rotating the main shaft of the drum 22, the belt-tread band T is stitched with a stitching apparatus (not shown) and pressure-bonded to the tire component K. Thus, the green tire is completed. Next, after the green tire is gripped by a conveying apparatus (not shown) from the radially outward, the air is exhausted from the space S. At the same time, by supplying the high-pressure fluid into the inner chambers 48a and 49a of the cylinder chambers 48 and 49, the bead lock segments 44 and 45 are moved radially inward, thereby transferring the green tire from the bead lock segments 44 and 45 to the conveying apparatus. Because the top of the outer surface of the outward-extending parts 58c and 59c of the sealing members 58 and 59 are given anti-stick treatment, they can be easily removed from the tire component K (the green tire) at this time.
Finally, the green tire is taken out of the tire molding drum 21 by the conveying apparatus. And by rotating the screw axis 23 reversely of the last time, the movable bodies 37 and 38, the bead lock segments 44 and 45, and the folding fingers 101 and 111 are restored to their original positions.
Patent document 1: Japanese Patent Application Laid-Open (JP-A) No. 2001-293793